


HorrorDust Week

by avosettas



Category: Undertale (Video Game)
Genre: Alternate Universe - Dusttale (Undertale), Dusttale Sans (Undertale), Horrortale Sans (Undertale), Horrortale Sans/Dusttale Sans (Undertale), M/M, Psychological Trauma, SOUL Mechanics (Undertale), Soul Bond
Language: English
Status: Completed
Published: 2021-03-15
Updated: 2021-03-21
Packaged: 2021-03-23 17:14:49
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 7
Words: 3,474
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30058836
Author URL: https://archiveofourown.org/users/avosettas/pseuds/avosettas
Summary: A collection of ficlets written for HorrorDust week, based on the prompts fromhere.
Relationships: Sans/Sans (Undertale)
Comments: 9
Kudos: 78





	1. souls

**Author's Note:**

> exciting!!! eso really enables me to write schmoopy horrordust So Much

"...are you... scared?" 

Horror's voice knocks him out of his reverie, where he'd been simply staring at his own soul like it would jump from his hands. 

It's not pretty, though Dust isn't sure souls are _meant_ to be pretty. But his certainly isn't; cracked deeply across its surface from trauma, its soft, membranous outer shell is hardened with LV. The whole thing glows brightly with magic, a bright lilac shade that's sharp on his sockets. 

In his cupped hands, it pulses erratically, like a frightened bird's broken wings, and Dust resists the urge to crush it like he would a roach. 

"not really," he says, but he knows Horror sees right through him. Horror _always_ sees right through him.

Horror's soul is in his own hands, curled delicately in his lap. Its pulse is much slower, not in calmness, but in weakness. Like Dust's, there are cracks in its LV-hardened shell, though shallower and fewer. And though it's tinted a pale red with DT, the whole thing is translucent, _wrong_ in a visceral way that even a LV-stained monster like Dust feels. 

A normal soul is unstained; perfect, pristine white. Dust doesn't think he knows anyone with a normal soul anymore. 

But even knowing that, Dust would argue Horror's soul is rather nice. Much nicer than his own.

"we don't… have to," Horror starts, and stops. His claws twitch, curling around his soul. It's probably an unconscious movement, but it makes Dust want to take his hand and hold it tightly. 

"y'want to, though?" Dust can't read him, too focused on his own anxiety to try to and decipher the look on Horror's face. 

"'course i do," Horror says easily. "ne'er wanted… anything else."

The erratic pulse of Dust's soul speeds up in his grip, and again, he resists the automatic urge to crush it. Instead, he ducks his head to stop himself from staring, and thrusts his hands forward towards his mate. 

Horror chuckles a bit. With one hand, he uncurls Dust's fingers from around his soul, though instead of plucking it from his hands, he gently guides Dust's hand closer to his own. In one hand, Horror now holds the tips of Dust's claws, nearly touching his soul; in the other is his own soul. 

"ready?" At Dust's jerky nod, he brings his hand towards his mate's. But he pauses suddenly - just as he's gingerly transferring his soul into Dust's hand and clutching it all at once - and says, "...love you, bunny." 

Dust can't get his response out, because everything contained in Horror's soul crashes over him at that instant. 

There's so much love there - for Dust, for his brother, for Aliza - but so much _regret_ too, so much bitterness. He can only imagine his own emotions are the same, a roiling ocean of guilt and shame that he's now subjected his mate to. 

Is there room in his soul for the love he has for Horror? Sometimes it feels like there isn't - his soul is full of shame and there isn't room for anything else. 

He gets flashes of memories - 

(a soul, a _human_ soul, pulsing steadily in a hand that isn't his; 

an excruciating pain behind his eye socket, on the crown of his skull; 

uncontrollable rage at someone, but he can't remember who - did he ever know who? 

someone telling him - not him, because he remembers hearing Nightmare tell _Horror_ \- to sleep, the feeling of cold slime on his forehead as they speak; 

his brother - no, _Horror's_ brother - and Aliza smiling widely, out of their home timeline, onto the next adventure, safe and recovering.)

He doesn't know when he leaned over, curling into a tiny ball on the bed - his elbows digging into his femurs, his hood hanging so low over his eyes that he can't see Horror. But his soul has returned to his own chest, beating steadily, much too fast. 

Beneath the steady rhythm of it, though, is something else. 

Dust pushes himself up slowly, one hand pressing to his chest as he moves. Under the steady pulse of his own soul is another, much slower beat, a _one-two_ to his _one-two-three-four_.

When he looks up, Horror is grinning almost madly at him, mirroring him with a hand pressed to his own chest. Dust feels as if he's going to pass out from the feeling of absolute adoration that passes from Horror's soul to his own.

He doesn't pass out, though. Instead, he collapses sideways, landing in Horror's lap with a soft huff. 

"love you too, big guy," he rasps.


	2. universes

**Notes for the Chapter:**

> i forgot to put context: it's been decided (with dust's input) that since dusttale is empty and dust barely visits, error can destroy it.

"i hate it here." 

Horror could imagine why; the reminder of how many had died would have been enough to bring a lesser monster to their knees. Not Dust, though. 

Maybe it's the guilt, but Dust is hunched over and shaking slightly, claws digging into the hems of his sleeves. He must be resisting the urge to grasp at his hood instead; every so often, Horror sees his arms twitch up, like they're about to bend at the elbows. 

He never lets them, though, forcing his hands to remain at his sides. 

"i… know," Horror replies, reaching to grab one. Dust's fingers shake even as he laces them with Horror's. "it'll be… gone soon, though." 

"i don't know if i want it to be gone," Dust confesses, staring down at the snow. It crunches beneath his feet with each step, and in some places, Horror thinks he sees the darker gray of monster dust mixed in with it. 

It's horrifying, but he's seen worse. Better dust on the ground than dust in his mouth, gritty between his teeth as he tries to swallow it down, because he hadn't known when his next meal would be… 

"y'okay?" Dust asks quietly as they step into Snowdin. The dust here is thicker; thankfully, it's mostly stuck to the snow, unable to be moved by the cave wind. 

"...mem'ries," Horror says, but he squeezes Dust's hand, knowing that the smaller's memories are likely worse. Clearer.

"yeah," Dust agrees, stopping in front of his mailbox. It's empty, and so is the one beside it, labeled _PAPYRUS_. 

His hand slips from Horror's, and there's a sudden clanging sound of metal against magic, metal against bone. When Horror finally processes it, he realizes that the sound was the mailbox being beaten into the ground. 

Dust stands above it, panting, each breath making his ribcage heave. The bone construct in his hand dissipates after a moment, and when he looks back up at Horror, his eyelights are wavering in their sockets. 

Only his own mailbox remains, labeled _sans._ , but it seems like he's considering destroying that one, too. 

Horror grabs his elbow instead, leading him gently towards the front door. The door is already ajar, so he simply shoulders it open without waiting for Dust. 

The house is as full of dust as the rest of the world, although it seems to be inorganic in this case, at least. Dust doesn't speak as he walks through it, clouds coming up beneath his feet as he crosses the carpet of the living room to the stairs. 

"wait for me?" he asks without turning, standing on the very bottom stair. His voice sounds strange, raspier than usual. Like he's crying. 

"'course i… will." 

Dust nods jerkily at that, and takes the rest of the stairs two at time, before disappearing into one of the bedrooms. Horror can't quite see in the dark of the house, but he thinks it was Papyrus's room. 

A door closes, and Horror shuts the front door behind him in answer. He considers sitting on the couch, but it's just as dusty as the rest of the house, and truth be told, Horror doesn't think sending himself into a coughing fit would be best for Dust's mental state. 

He leans on the wall instead, mumbling the ingredients for Dust's favored meals to himself. He'll make one of those when they return to Nightmare's castle, and then they'll get some much-needed sleep. It wouldn't do to let Dust dwell on this, after all. 

Eventually, Dust stomps back down the stairs, his lower legs and sneakers covered in his namesake, and Horror can't help a small chuckle. There isn't anything in his little mate's hands; they're as empty as they were when he went upstairs. 

But when he says, "ready?" without meeting Horror's eyes, Horror just nods. Really, he's not sure if _Dust_ is ready - to leave his home, and to leave this place where his sins could eat him alive - but he won't question it. 

If Dust wants to leave, Horror won't tell him that he can't. 

Instead, he takes Dust's hand, barely jolting when the charged magic of the other's LV shocks him like a broken wire, and waits for the universe to go topsy-turvy. He's not concerned as to whether that will take five minutes or five hours, though. 

As far as he's concerned, it's Dust's call.


	3. family

"what do you think of… humans?" Horror asks one day, as he's slowly stirring the ingredients for banana bread together. 

The question makes Dust pause from his book without looking up, and a child's laughter echoes in his skull. Instead of answering immediately, he closes his eyes, and tries to recite what he's read: _The most potent toxin present in the_ Amanita _genus of mushrooms is alpha-amanitin. The genus includes the death cap mushroom, which accounts for…_

"...don't like them much," he answers eventually, just before he gets to death statistics. 

"oh," Horror says without turning, carefully folding the batter over itself with a rubber spatula. "was… wondering if you'd wanna meet _my_ human. she's… a good one, promise." 

Again, a child laughs, and this time Dust slams his hands on the table, and shouts "shut UP!" at them. Except the chair across from him is empty. The only one at the table is him. 

His claws score deep lines into the tabletop, and he laughs a bit, but there are tears landing on the closed cover of _Poisonous Mushrooms of the World_. 

There's a warm hand on his back, and it takes him longer than it should to connect it to the empty space by the stove. Horror eases him back into his chair with rumbly hum, and then pulls the other chair around to sit beside him, settling into it with a rather foreboding creak. 

"sorry," Horror says softly. "i… know y'got issues with humans… aliza's different from the ones who… hurt us, though." 

Logically, Dust knows this. He's heard about Aliza - and Sycamore, Horror's brother - offhandedly before, knows that she fell Underground during the famine in Horror's world, and was one of the few to escape to the Omega Timeline. She lives with Sycamore, and according to Horror, she's "sweet as pie". 

The conversation just hasn't been framed this way. Like Dust is a bomb about to go off, which he supposes he is. 

"i don't want… you getting hurt," Horror continues, and Dust blinks, finally turning to look at him. 

"what about her?" 

"'s you i'm… worried about. know you got your hangups." 

Hangups is a nice way of putting it. The kid had destroyed his entire Underground hundreds and thousands and millions of times over, and turns him into a _murderer_. The only thing left of Dust has left of his universe is himself and the dust that follows him no matter where he goes. 

His claws dig into his shorts. "i don't like humans," he repeats.

"that's okay," Horror says easily. "no pressure." He leans back in his chair, pulling one of Dust's hands from where it claws at his shorts, and taking it with him, holding it to his ribs. His fingers stroke over the scarred bones slowly, and he adds idly, "i could see if paps wants to come here for dinner. they're… both eager to meet you, but aliza's a good kid. she'll… understand if it takes you a while to… be comfortable meeting her." 

"she isn't the one who destroyed your -" Dust begins, wanting to clarify, but Horror cuts him off.

"no," he says firmly - not angrily, but stern, like he hates to even consider it. "aliza… is a good kid. frisk. i hope they rot in hell." 

Dust nods in agreement, slumping sideways to lean against Horror, following the tug of the hand in his mate's grip. Horror doesn't seem to mind; he switches hands, throwing his now-free arm around Dust's shoulders and pulling him close. 

"tell me… about poisonous mushrooms?" he asks Dust after a moment, and Dust is all to happy to oblige, even if the change in subject is as obvious as could be.


	4. fighting together

**Notes for the Chapter:**

> this chapter contains (what i think are) **graphic depictions of violence**! 
> 
> it's also really short bc i can't write action scenes!

Dust has already gotten a hit in before Horror's axe lands. The purple end of one of his poison-tipped bone constructs is sticking out of the guard's shoulder, and their right arm now hangs limp beneath the puncture. 

Horror's axe lands a smidge closer to their neck than Dust's bone construct did, and the guard howls in agony. It takes a moment to dislodge - it cut through layers of armor, flesh, muscle, _and_ bone, after tall - and then Horror is crouching, quick as he can with his slow movements. 

Dust doesn't have to even say it anymore - they've perfected this dance after years of being partnered together under Nightmare's orders, of being together even outside of the missions they've been sent on - but he still does, just in case, a tiny whisper of "duck." 

Then, another bone construct lodges itself into the guard's shoulder, lower this time, in the fleshy area where their chest and arm meet, and then Dust is on them, driving it still deeper. He growls when they scream, a wordless cue for Horror. 

He swings his axe one-handed, and it embeds itself in the guard's stomach. Their shriek of pain cuts off abruptly, and dust covers the ground. 

Both of Dust's bone constructs dissipate, and he comments monotonously, "that was boring."


	5. with/around others

**Notes for the Chapter:**

> this is the last chapter i have prewritten, but i'm excited to start working on tomorrows prompt!! not sure what i'll do for the free day though...

Dust is quiet where he lays in Horror's lap, but he isn't asleep. Horror is sure of this; his breathing is too fast, and his extremities twitch intermittently. It's most noticeable in his fingers, curled into loose fists near his face. Every time one of them fidgets, the movement rustles the bottom of Horror's shirt, the sensation almost ticklish against his ribs. 

His eyes are shut, at least, and Horror muses that, at the very minimum, it's nice to see his little mate so relaxed, even if he isn't asleep. Of course, he'll probably be startled out of it the moment someone else sits on the couch, but... 

Well, for now Horror thinks it's nice. Dust needs his rest, after all - all of them do. Between nightmares and insomnia, none of the inhabitants of the castle get enough rest, and Dust least of all. 

(Horror might be biased on that opinion, though, since he shares a bed with Dust every night. He's privy to all the tossing and turning, and the screaming and crying his little mate suffers from.)

No sooner than these thoughts make their way through Horror's slow mind, Killer plops himself down on the cushion on his right. Dust's legs take up most of the cushion to Horror's left, but he draws them closer to himself at the couch's movement, fist clenching as his sockets open. His eye lights are foggy but clearly annoyed. 

"woke me up," he grumbles at Killer, reaching out to swat at him with one hand. Killer just laughs, batting his hand away easily. 

Horror keeps quiet as he watches them, because he knows Dust wasn't asleep, but he certainly shares the sentiment. 

He definitely doesn't mind when Dust decides to climb onto him, clinging like a koala, as a result of Killer's teasing. He buries his face in Horror's hood, grumbling something incoherent as he clutches at his mate's shoulders.

Apparently, Dust's movement is the cue Cross needs to settle himself on the vacated cushion, though he isn't as annoying as Killer is. "We should watch a movie 'til the boss gets back." 

"'f y'like," Dust grunts, muffled. "fuckers woke me up." 

"y'weren't… asleep," Horror finally points out, though his tone is teasing. "was a lot quieter before killer showed up, though." 

"just for that," Killer declares, " _i'm_ picking the movie." 

"Go for it," Cross says, while Horror just shrugs slightly, and Dust groans. 

"put on whate'er the fuck you want," he complains. "long as you shut up once it's on." 

"sure, fine, whatever," Killer agees, already flipping through their DVDs. "any preferences?" 

"nah," Horror tells him, because he knows that no matter what movie Killer picks, he'll end up staring at Dust, still resting curled into his chest. 

That's what always happens, when they watch movies. There's no reason today should be any different. 

(And it isn't.)


	6. LOVE/love

**Notes for the Chapter:**

> sorry this is late, i had a hard day and then, frankly, forgot about posting this even though it was finished

"i love you," Horror says one day as they lay together in his bed. 

Dust's fist curls tighter in Horror's hoodie, and he ducks his head to avoid looking at him. He can't bring himself to pull away from the other, though, too drawn to his affection and warmth. 

But quite frankly, Dust doesn't know if he can return that sentiment. There's so much LV in his soul, he doesn't know if he's even capable of love anymore. Any emotions that aren't rage or guilt have been quashed by his LV. 

_Do you remember how Nightmare reacted, brother? His face was incredible._

(Nightmare's face had fallen, the first time he'd checked Dust.)

_Most monsters top out at LV 20, don't they? What was it that monster said…?_

(Before he'd killed them - he couldn't even remember what universe it was, or why he was there, now - they'd whispered that they'd never seen a monster who's LV read only **20+** on a CHECK.)

"...dust?" 

He doesn't know if he can manage words, but he tries. "wh - wh - why." 

It's so stilted and awkward; there's no way he could ever explain himself, not in this state. He can barely even raise his head, and when he does manage to do that, there's a wet spot where his face was. 

Horror doesn't say anything, only raises a hand to cradle Dust's cheek. With his thumb, he wipes away the tears gathering beneath the rim of Dust's eye socket, and the motion is so slow and tender that it feels reverent. 

"what… do you mean?" he asks finally, still stroking Dust's cheek.

"do you know how much LV i have," Dust chokes out in response, instead of answering. As far as he knows, Horror is the only one in the castle with no LV. It's farfetched to think he'll be disgusted with Dust, but…

_He'll be afraid of you, I'm sure. Even Killer is only LV 19._

But Horror mumbles his assent. "mhm… y'got a lot, dont'cha?" 

"check me," Dust orders miserably. And Horror does; there's a telltale _ping!_ of magic, but his face doesn't change. 

"yeah… a lot," Horror repeats. "never seen… a check like that. doesn't change much, though." 

"but -" 

"check me, lambchop," he interrupts, and Dust stares. 

_ping!_

And… Horror has LV. It's not a meager amount, either. Somehow, that surprises Dust. 

"so?" 

"i - i'm. i." 

"don't have to say it back, if y'can't," Horror assures him. "but it ain't got nothin'... to do with your LV." 

"i love you too," Dust whispers finally, right on the heels of Horror's words. For a moment, he feels ashamed for interrupting, but Horror's resulting purr is worth it. 

So, so worth it.


	7. free day!

Dust is bleeding when he comes into the kitchen. 

Horror can tell immediately, but the underlying floral scent clinging to his little mate calms him slightly - he's probably cut himself while gardening. He turns from the stove, and Dust stiffens like a deer in headlights. His hands are bloody, and there are thorns caught on the tattered wrists of his hoodie. 

"you… okay?" Horror asks. Dust seems fine; it's likely he's simply trying to keep a secret, rather than toppling on the edge of an episode. 

"yeah, fine," Dust replies. "have you got any shears?" 

"'course… what happened… to your hands?" 

"huh?" Dust blinks, as if just noticing them. "uh, nothin'." 

Horror raises a brow, but holds out his kitchen shears to the other anyway. "make sure… you come back so i… can patch your hands up. when you're done, i mean."

"yeah, i will. promise," Dust says, and then he's gone. 

Horror can't be mad, considering Dust gave him a _promise_. He's not sure if anyone in the castle hates promises more than Dust does. 

(And when he comes back to keep his promise by letting Horror fix up his hands, he has a handful of thornless-roses, too.)

(Horror can never stay mad at his little mate. But he will be investing in a pair of thick gardening gloves for him as soon as he can.)

**Notes for the Chapter:**

> so concludes horrordust week! i wish i'd been able to do longer pieces but i'm a little burnt out; prompt things always end up like this for me ;w;
> 
> twitter @avosettas if you wanna chat!

**Author's Note:**

> twitter @avosettas


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